This subject have come up multiple times, and is still not available in game. Personally I think it's a very basic staple for a lot of healers, something I myself have used for years playing both WoW and RIFT. It's a matter of playstyle and mouseover healing makes healing more enjoyable for myself. I'm probably not going to heal for starters in this game because of this and I'm worried the group finding will suffer because of this as well.
I fully understand why Bioware don't want macros in the game, because macroing together abilities to trivialize rotations and so on is bad. However, that's not an excuse for leaving mouseover healing out of the game. You can do stuff differently. You can add a mouseover healing options menu where you could create skill buttons for dedicated healing, buffing and debuff removal on mouseover.
It'd look much like the traditional macro frame, but in one column you have a list of your available skills you could make mouseover. You click the skill and it pops up in another column as a mouseover skill, which you can drag to your actionbar.
I love mouseover healing, click healing just feels clunky.
EDIT: There have been confusion of what mouseover healing actually is. Mouseover healing is hovering your mouse over either the raid/group frames or a player and hit a spell on your keyboard to achieve the same thing as clicking that raid/group frame or player and pushing the button. In WoW it was achieved through macros such as:
/cast [target=mouseover] Rejuvenation
